Help CCS for 1.33mA

[merlin el mago]

Thanks Hego.

The question is: I need to run the 7N7 so low: 1.33mA biased 82V?

I don't have any problem to used more volts for the 7N7 keeping the 170V for the 6AS7, I'm looking for the best SQ possible with the combo 7N7+6AS7.

The 7N7 tube seller told me the tubes spot on 9mA, attached trioda simulation, it's OK?

 

[artosalo]

How to adjust voltage, like artosalo schematic?

At first you adjust the CCS to the current you want.
Then you adjust the cathode resistor of 6SN7 / 7N7.
This varies the plate voltage only, not plate current, since CCS keeps it constant.

I'm looking for the best SQ possible with the combo 7N7+6AS7.

I don't know what sounds best for your ears, so you have to search it by yourself.

 

[merlin el mago]

I'm expressed very bad, in place best SQ I have to say best operation points for both tubes.

 

[merlin el mago]

Add C3 and change R2 to 1k8. Then gain is 12 dB.

Please artosalo could you post the .asc file for LTSpice?

 

[artosalo]

Here almost the same circuit:

 

[merlin el mago]

Thank you.

 

[merlin el mago]

LTSpice don't let me simulate open window (could not open file "tubelibrary.inc.")

 

[artosalo]

Here:

 

[merlin el mago]

Thanks, how to use it or installing?

 

[TasoTaso]

Low current, high-Z CCS from my book.

Hi, can I ask you something about the image you posted? Thanks 🙂